JP2672354B2 - Polypropylene resin composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a polypropylene resin composition, and more particularly to a polypropylene resin composition for adhesives between a polypropylene layer and an ethylene-vinyl alcohol copolymer or nylon layer.

[Conventional technology]

Laminates composed of a polypropylene resin and an ethylene-vinyl alcohol copolymer or a polypropylene resin and a nylon have low oxygen permeability and low water vapor permeability, so that they are widely used for food and medicine containers.

However, since the polypropylene resin layer and the ethylene-vinyl alcohol copolymer or nylon layer have poor adhesion to each other, the lamination is usually carried out by a co-extrusion molding method in which an adhesive layer is provided between each resin layer. Is being done.

As the resin used for the adhesive layer, for example, a polyolefin resin graft-modified with an unsaturated carboxylic acid or a derivative thereof is well known (JP-A-48-5527,
See JP-A-51-98784 and JP-A-52-26548.

As a method of improving the adhesive force between these resin layers,
Method of adding low-density polyethylene to the graft-modified polyolefin resin (see Japanese Patent Publication No. 54-40113, etc.), method of adding ethylene polymer polymerized by the medium and low pressure method (see Japanese Patent Publication No. 59-36586, etc.) ), And a method of adding a hydrocarbon elastomer (Japanese Patent Publication No.
-40112, etc.) are known.

[Problems to be solved by the invention]

However, even if a composition obtained by adding low density polyethylene, an ethylene polymer or a hydrocarbon elastomer to the above graft-modified polyolefin resin is used as an adhesive layer, the performance is insufficient. When a laminate comprising a vinyl alcohol copolymer or a polyamide layer is blow molded into a bottle, the adhesive strength of the thin portion of the product is low, and therefore improvement is required.

[Means for solving the problem]

Therefore, the present inventors have prepared a modified polypropylene resin graft-modified with an unsaturated carboxylic acid as an adhesive layer of a polypropylene resin and an ethylene-vinyl alcohol copolymer or nylon, or a modified polypropylene resin and an unmodified polypropylene resin, and an amorphous A polypropylene resin having a very high adhesive strength by using a composition comprising a specified amount of an olefin copolymer and a specific ethylene-α-olefin copolymer, and particularly having a sufficient adhesive strength even in a thin portion of a product. The present invention has been completed and the present invention has been completed.

That is, the present invention relates to a modified polypropylene resin graft-modified with an unsaturated carboxylic acid or a mixture of the modified polypropylene resin and an unmodified polypropylene resin (A), a substantially amorphous α-olefin copolymer (B), And the density is 0.
860g / cm ³ or more and less than 0.910g / cm ³ , 50% n-hexane insoluble matter
Ethylene-α with a melting point of 100 ° C or higher and a weight percentage of 100% or higher
-Olefin copolymer (C) (hereinafter abbreviated as ULDPE), (A) 99-51 wt%, (B) + (C) 1-49
Polypropylene resin composition for adhesive material between polypropylene resin layer and ethylene-vinyl alcohol copolymer or nylon layer, wherein (B) / (C) is 99/1 to 1/99 (weight ratio) in weight%. In the polypropylene resin composition, the substance, and the substantially amorphous α-olefin copolymer (B) is an ethylene-propylene copolymer rubber.

The modified polypropylene resin (A) used in the present invention is a crystalline polypropylene resin such as a homopolymer of propylene or a copolymer of propylene and other α-olefin,
Acrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride and the like graft-modified, specifically, for example, as described in JP-B-59-43045 What was obtained by the method etc. can be used.

The modified polypropylene resin obtained by the above method can be used as it is, but in consideration of cost, a modified polypropylene resin having a high graft ratio of unsaturated carboxylic acid is produced, and this is mixed with a crystalline polypropylene resin. The amount of the grafted unsaturated carboxylic acid (graft ratio) contained in the polypropylene resin composition of the present invention is 0.01 to 2 although the mixing ratio varies depending on the graft ratio of the modified polypropylene resin. weight%
It is preferably about this. If the graft ratio is less than 0.01% by weight, the adhesive strength will be low, and if it exceeds 2% by weight, the adhesive strength will be rather lowered and the resulting composition will be easily colored and the cost will be high, which is not preferable.

The crystalline polypropylene resin used as the raw material of the modified polypropylene and the crystalline polypropylene resin to be mixed with the modified polypropylene later may be the same or different, but it is not particularly necessary to support them, but as a raw material of the modified polypropylene, in terms of productivity. A propylene homopolymer is preferable, and a copolymer with 10% by weight or less of ethylene is preferable in consideration of the adhesiveness of the composition to be obtained, which is to be used in later mixing.

A representative example of the substantially amorphous α-olefin copolymer (B) used in the present invention is an ethylene-propylene polymer rubber (EPR) (this includes an ethylene-propylene-diene copolymer rubber (EPDM ) Are included), and other examples include ethylene-butene-1 copolymer rubber (for example, Mitsui Petrochemical “Tufmer A”) and propylene-butene-1 copolymer rubber. Most of these copolymers have a density of about 0.86 to 0.88 g / cm ³ and overlap with the range of ULDPE, but since they are amorphous, they have no n-hexane (C ₆ ) insoluble content.
It is clearly distinguished from ULDPE in that it is less than 50% by weight and has a melting point (Tm) of less than 100 ° C.

ULDPE (C) used in the present invention is ethylene and has 3 carbon atoms.
It is a copolymer with .about.12 .alpha.-olefin.

Specific examples of α-olefins include propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, dodecene-1. The content of the α-olefin in the ethylene-α-olefin copolymer is preferably 2 to 40 mol%, more preferably 5 to 20 mol%.

ULDPE (C) used in the present invention has a density of 0.860 g / cm ³ or more and less than 0.910 g / cm ³ , a C ₆ insoluble content of 50 wt% or more, and a Tm of
It exists at 100 ° C or higher, and if the density is less than 0.860 g / cm ³ , the rigidity of the obtained product will be low,
If it is 0.910 g / cm ³ or more, the adhesiveness to the ethylene-vinyl alcohol copolymer and nylon is low, and the adhesive force particularly to the thin portion becomes insufficient. Further, when the C ₆ insoluble content is less than 50% by weight or the Tm is less than 100 ° C., the rigidity of the obtained product is lowered, and in any case, the effect of the present invention is not exhibited.

Hereinafter, a method for producing ULDPE (C) used in the present invention will be described.

First, the catalyst system used is a combination of a solid catalyst component containing magnesium and titanium and an organoaluminum compound. As the solid catalyst component, for example,
Double salts, double oxides, carbonates, chlorides or hydroxides containing magnesium, such as metal magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, or a metal selected from silicon, aluminum, and calcium and a magnesium atom In addition, known methods of treating these inorganic solid compounds with an oxygen-containing compound, a sulfur-containing compound, an aromatic hydrocarbon, a halogen-containing substance, or reacting a titanium compound with a magnesium-containing inorganic solid compound such as a reaction product thereof. And the like.

Examples of the oxygen-containing compounds include organic oxygen-containing compounds such as water, alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, polysiloxanes, and acid amides, and inorganic oxygen-containing compounds such as metal alkoxides and metal oxychlorides. And oxygen compounds. Organic sulfur-containing compounds such as thiol and thioether,
And inorganic sulfur compounds such as sulfur dioxide, sulfur trioxide and sulfuric acid. As the aromatic hydrocarbon, benzene,
There are various mono- and polycyclic aromatic hydrocarbon compounds such as toluene, xylene, anthracene, and phenanthrene. Examples of the halogen-containing substance include compounds such as chlorine, hydrogen chloride, metal chlorides, and organic halides.

Examples of titanium compounds include titanium halides, alkoxy halides, alkoxides, and halogenated oxides. As the titanium compound, a tetravalent titanium compound and a trivalent titanium compound are preferable, and as the tetravalent titanium compound, specifically, a compound represented by the general formula Ti (OR) _n X _4-n is preferable. . Here, R represents an alkyl group, an aryl group or an aralkyl group having 1 to 20 carbon atoms, X represents a halogen atom, and n is 0 ≦ n ≦ 4. For example, titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monomethoxytrichlorotitanium, dimethoxydichlorotitanium, trimethoxymonochlorotitanium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium, tetra Ethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, triisopropoxymonochlorotitanium, tetraisopropoxytitanium, monobutoxytrichlorotitanium, dibutoxydichlorotitanium, monopentoxytrichlorotitanium, monophenoxytrichlorotitanium, diphenoxydichloro. Examples include titanium, triphenoxymonochlorotitanium, tetraphenoxytitanium and the like.

The trivalent titanium compound is obtained by reducing titanium tetrahalide such as titanium tetrachloride or titanium tetrabromide with hydrogen, aluminum, titanium or an organometallic compound of a metal belonging to Group I to Group III of the periodic table. And titanium trihalide. A tetravalent compound represented by the general formula Ti (OR) _m X _4-m (R represents an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, X represents a halogen atom, and m represents 0 <m <4). And a trivalent titanium compound obtained by reducing the halogenated alkoxytitanium with an organometallic compound of a metal belonging to Group I to Group III of the periodic table.

Of these titanium compounds, tetravalent titanium compounds are particularly preferred.

Examples of other catalyst systems include a catalyst system in which a reaction product of an organic magnesium compound such as a so-called Grignard reagent and a titanium compound is used as a solid catalyst component, and an organic aluminum compound is combined with the reaction product. . Examples of the organomagnesium compound include, for example, organomagnesium compounds such as RMgX, R ₂ Mg, and RMg (OR) (R is an organic residue having 1 to 20 carbon atoms, X is a halogen atom)
And their ether complexes, and also these organomagnesium compounds with other organometallic compounds, for example,
Those modified by adding various compounds such as an organic sodium compound, an organic lithium compound, an organic potassium compound, an organic boron compound, an organic calcium compound, an organic zinc compound, and an organic aluminum compound can be used.

Examples of other catalyst systems include, as a solid catalyst component,
Using a solid substance obtained by contacting an inorganic oxide such as SiO ₂ and Al ₂ O ₃ with the solid catalyst component containing at least magnesium and titanium, and exemplifying a combination of an organic aluminum compound with the solid substance. Can be. As the inorganic oxide, in addition to CaO of _{SiO 2, Al 2 O 3,} B 2 O 3, SnO 2 , etc. can be mentioned, also it can be used without any trouble double oxides of these oxides.

Specific examples of the organoaluminum compound to be combined with the solid catalyst component described above include general formulas R ₃ Al, R ₂ AlX, and R
Organoaluminum compounds of AlX ₂ , R ₂ AlOR, RAl (OR) X and R ₃ Al ₂ X ₃ (R is an alkyl group having 1 to 20 carbon atoms, an aryl group or an aralkyl group, X is a halogen atom, and R is
May be the same or different) are preferred, and triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctyl aluminum, diethyl aluminum chloride, diethyl aluminum ethoxide, ethyl aluminum sesquichloride, and mixtures thereof. And so on.

Although the amount of the organoaluminum compound is not particularly limited, it can be usually used in an amount of 0.1 to 1000 mol times based on the titanium compound.

The copolymerization reaction is carried out in the same manner as the usual olefin polymerization reaction using a Ziegler type catalyst. That is, all reactions are carried out in a state substantially free of oxygen, water and the like, in the presence of a gas phase or an inert solvent, or using the monomer itself as a solvent. The conditions for the copolymerization of ethylene and α-olefin, the temperature is 20 ~ 300 ℃, preferably 40 ~ 200 ℃,
Pressure is normal pressure or 70 kg / cm ² · G, preferably 2 kg / cm ² ·
G or 60 kg / cm ² · G. Although the molecular weight can be adjusted to some extent by changing the conditions such as the copolymerization temperature and the molar ratio of the catalyst, it can be effectively performed by adding hydrogen to the polymerization system. Of course, a multi-stage polymerization reaction of two or more stages having different polymerization conditions such as hydrogen concentration and polymerization temperature can be carried out without any trouble.

The method for measuring the C ₆ insoluble matter and Tm in the present invention is as follows.

<Measurement method of C ₆ insoluble content> A hot press was used to form a 200 μm thick sheet.
Three 0 mm x 30 mm sheets are cut out, and the sheets are extracted with boiling n-hexane for 5 hours using a double tube Soxhlet extractor. The C ₆ insoluble matter is taken out, and after vacuum drying (7 hours, under vacuum, 50 ° C.), the C ₆ insoluble content is calculated by the following equation.

<Method of measuring Tm by DSC> About 5 mg of sample was weighed from a 100 μm thick film hot-pressed, set in a differential scanning calorimeter, heated to 170 ° C, and kept at that temperature for 15 minutes. After holding
Cool to 0 ° C at a cooling rate of 2.5 ° C / min. Next, the temperature is increased from this state to 170 ° C. at a rate of 10 ° C./min, and measurement is performed. The temperature at the peak position of the maximum peak among the peaks that appeared during the temperature rise from 0 ° C. to 170 ° C. is defined as Tm.

The addition ratio of the modified polypropylene resin (A) in the present invention needs to be in the range of 99 to 51% by weight with respect to 100% by weight of the composition. If the addition ratio exceeds 99% by weight, the adhesive strength to the ethylene-vinyl alcohol copolymer and the nylon layer is low, and if it is less than 51% by weight, the adhesive strength to the polypropylene resin layer is low, which is not preferable.

In addition, amorphous α-olefin copolymer (B) and UL
The addition ratio of DPE (C) is 1 to 49% by weight of (B) + (C) and (B) / (C) = 99/1 to 1/99.
When the amount of (B) + (C) is less than 1% by weight, the adhesive strength with the ethylene-vinyl alcohol copolymer and the nylon layer is low,
If it exceeds 49% by weight, the adhesive strength with the polypropylene resin layer will be reduced, and if a material other than the range of (B) / (C) = 99/1 to 1/99 (weight ratio) is used, ethylene-vinyl alcohol In either case, the adhesive strength to the polymer or nylon layer is low, especially in the thin portion of the product, which is not preferable.

In the polypropylene resin composition of the present invention, other resins and additives as required, for example, ordinary medium and low density polyethylene, high density polyethylene, ethylene-vinyl alcohol copolymer, resins such as nylon, antioxidants, An ultraviolet absorber, a pigment, a dye, a filler, a nucleating agent, an antiblocking agent, a slip agent, an antistatic agent, a flame retardant and the like may be added within a range not impairing the object of the present invention.

The resin composition of the present invention is usually obtained by preliminarily mixing the components with a Henschel mixer or the like, and then melt-kneading them with a single-screw or twin-screw extruder or the like to form pellets.

When a multilayer laminate comprising an ethylene-vinyl alcohol copolymer or a nylon and a polypropylene resin is produced using the resin composition of the present invention, it can be produced by the following method.

The polypropylene, ethylene-vinyl alcohol copolymer, and nylon used in this case are not particularly limited, and generally known ones can be used. In addition, these are, if necessary, known additives such as an antioxidant, an ultraviolet absorber, a pigment, a dye, a filler, a nucleating agent,
It may contain an antiblocking agent, a slip agent, an antistatic agent, a flame retardant and the like.

As a specific method for producing a laminate, a polypropylene layer, a resin layer made of an ethylene-vinyl alcohol copolymer or nylon, and a film and a sheet of an adhesive layer are produced in advance, and the adhesive layer is replaced with another film. A film of resin, a method of thermocompression bonding between sheets, a film of either a resin consisting of polypropylene and ethylene-vinyl alcohol copolymer or nylon, the molten adhesive layer composition is extruded on the sheet, and the other resin is further extruded. The method of laminating films, sheets of polypropylene, a resin made of polypropylene, an ethylene-vinyl alcohol copolymer or nylon, an adhesive layer composition melted by an extruder and coextruded by the same die can be employed.

The extrusion temperature for extruding a resin made of polypropylene, an ethylene-vinyl alcohol copolymer or nylon may be a conventional extrusion temperature. The extrusion temperature of the adhesive layer composition is 190 to 300 ° C, preferably 200 to 280 ° C.

The thickness of the adhesive layer is preferably in the range of 0.005 to 0.1 mm.
If it is less than 0.005 mm, sufficient adhesive strength cannot be obtained. Further, even if the thickness is increased beyond 0.1 mm, the adhesive strength does not increase.

Examples of the shape of the laminate include a container such as a film, a sheet, a pipe, a corrugated sheet, a bottle manufactured by injection molding or blow molding. Also, after the laminated sheet is manufactured in advance, it is also possible to manufacture various containers and the like by a method such as vacuum forming and pressure forming.

〔Example〕

Hereinafter, the present invention will be described with reference to examples. In the following description, the adhesive strength is in accordance with JIS K-6854 (T-type peel test), the melt index (MI) of polypropylene and the amorphous α-olefin copolymer is in accordance with JIS K-6758, and the density is JIS. It was measured according to K-6760.

350 g of crystalline polypropylene resin (propylene homopolymer with MI = 8) and 3500 ml of chlorobenzene were charged into the autoclave of Examples 1 to 135, and the temperature was raised to 130 ° C. with stirring, followed by di-t-butyl peroxide. A solution prepared by dissolving 35 g in 140 ml of chlorobenzene and a solution prepared by dissolving 50 g of maleic anhydride in 80 ml of acetone were charged in 4 hours. After the completion of charging, stirring was continued for another 3 hours at 130 ° C. to complete the reaction. The reaction was performed under a nitrogen atmosphere.

After cooling, the slurry is washed with a large amount of acetone, filtered and dried to perform grafted polypropylene resin (GPP)
I got The graft ratio of maleic anhydride to this resin was 11.5 wt% by IR measurement.

The GPP, ethylene content of 4.5% by weight, and the ethylene-propylene random copolymer (PP) having an MI of 1.5 g / 10 min, the amorphous α-olefin resin shown in Tables 1 and 2 and ULDPE are shown in Table 4.
Further, 0.3 part by weight of calcium stearate, 0.25 part by weight of tris (2,4-di-t-butylphenyl) phosphite, and pentaerythrityl-tetrakis [3- ( 3,5-di-t-
Butyl-4-hydroxyphenyl) propionate] 0.
Add 3 parts by weight and mix with a Henschel mixer, then 230 ℃
Was pelletized with a 40 mmφ uniaxial extruder to obtain a resin composition for an adhesive layer.

The above composition and polypropylene "Mitsui Noblen MJS-
G "(trademark, manufactured by Mitsui Toatsu Chemicals, Inc., MI1.0) and ethylene-vinyl alcohol copolymer" Eval F "(manufactured by Kuraray, MI1.3) are polypropylene layers / adhesives using a feed block die. Layer / ethylene-vinyl alcohol copolymer layer / adhesive layer / polypropylene layer coextrusion of 3 types to form a parison with an outer diameter of 39 mmφ and a wall thickness of 4 mm, and then blow molding (air pressure 5.0 kg / cm ² ), A container with a capacity of 850cc was molded (product weight is 56g, product outer diameter is 90mmφ).
Supply of each resin to the feed block, polypropylene layer 40mmφ extruder, adhesive layer composition 30mmφ extruder, ethylene-vinyl alcohol copolymer layer 30mmφ
An extruder was used.

Then, the side wall portion of the container was removed, and the peel strength was measured.

The extrusion temperature was 200 ° C. for each resin, and 200 ° C. for the die and feed block.

The thickness of the peel strength measurement part is polypropylene layer / adhesive layer / ethylene-vinyl alcohol copolymer / adhesive layer / polypropylene layer = 0.45 / 0.0
It was 3 / 0.04 / 0.03 / 0.4 mm.

 Table 4 shows the results.

Comparative Examples 1 to 7 Tests were conducted in the same manner as in Examples 1 to 13 using the formulations having the compositions shown in Table 5. In addition, the polyethylene (PE) shown in Table 3 was used for Comparative Examples 3-4.

 Table 5 shows the results.

Example-14 Instead of the ethylene-vinyl alcohol copolymer in Example 1, "UBE Nylon 1011"(trademark; Ube Industries, Ltd.)
The same test as in Example 1 was conducted except that the extrusion temperature of nylon was 250 ° C., the temperature of the feed block was 250 ° C., and the temperature of the die was 245 ° C. The thickness of the part where the peel strength was measured at this time was as follows: polypropylene layer / adhesive layer / nylon layer / adhesive layer / polypropylene layer = 0.45 / 0.04 / 0.
It was 03 / 0.04 / 0.4 / mm.

 The peel strength was 2.8 kg / cm.

〔The invention's effect〕

When the resin composition of the present invention is used as an adhesive layer, the adhesion between the polypropylene layer and the ethylene-vinyl alcohol copolymer or nylon layer is very high, and when the product is molded by blow molding, vacuum molding, etc. It is possible to manufacture a container having sufficient adhesive strength even in parts.

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Claims (2)

(57) [Claims] 1. A modified polypropylene resin graft-modified with an unsaturated carboxylic acid or a mixture thereof (A) with an unmodified polypropylene resin, a substantially amorphous α-olefin copolymer (B),
And an ethylene-α-olefin copolymer rubber (C) having a density of 0.860 g / cm ³ or more and less than 0.910 g / cm ³ , an n-hexane insoluble content of 50% by weight or more and a melting point of 100 ° C. or more, A polypropylene resin layer in which (A) is 99 to 51% by weight, (B) + (C) is 1 to 49% by weight, and (B) / (C) is 99/1 to 1/99 (weight ratio). A polypropylene resin composition for an adhesive between an ethylene-vinyl alcohol copolymer or a nylon layer. 2. The polypropylene resin composition according to claim 1, wherein the α-olefin copolymer (B) which is substantially amorphous is an ethylene-propylene copolymer rubber.